Here's the script for the original ending (which was filmed and then deleted at the last minute because the movie was running too long):
The tense, silent shock of the Senate floor is broken and men start for Jeff's inert form. A tumult goes up, and JEFFERSON is seen inert--completely gone--as men surround him. And then--suddenly--off-scene--a pistol shot is heard. Heads turn violently in the direction of the cloak room. Women scream. In the CLOAK ROOM, near the door to the Chamber, Paine is now struggling with three or four men, who wrest a revolver out of Paine's hand. In violent desperation, Paine tears himself loose and rushes for the chamber. In THE CHAMBER Paine comes toward the center aisle. (Jefferson still lying face down on the floor.)
PAINE (crying out to the Chair): Expel *me*! Not him. *Me*!
He continues toward the chair as he talks--a man distracted-- the whole house on its feet.
PAINE: Willet Dam is a fraud! It's a crime against the people who sent me here--and *I* committed it! [PAINE walks mechanically toward the chair.] Every word that boy said is the truth! I'm not fit for office! I'm not fit for any place of honor or trust in this land! Expel me--!
SAUNDERS (wildly, clutching Diz): He did it.
DIZ: Wait a minute. I've got to write this story.
PRESIDENT (pounding vainly with his gavel): Order, gentlemen, please.
DIZ (to Saunders): Will you please let go of me.
SAUNDERS (screaming): He did it! Yippee!
The scene dissolves to the HOPPER KIDS, a newspaper between them--and just yelling at the tops of their lungs:
And this is followed by a BONFIRE SCENE, with Boy Rangers leaping and yelling; and then we see the WINDOW of the offices of the JACKSON CITY PRESS at night, where a rock goes crashing through the window, smashing it to smithereens. This dissolves to HOPPER'S EXECUTIVE OFFICE, in which HOPPER is surrounded by Edwards and the other members of the Citizen's Committee. Happy is a lion at bay.
HUBERT (yelling into their teeth--in violent indignation): Resign! Resign! Who found this magnificent young American? Who went down alone--in the dead of night--and sought out this Lincoln--this-- Resign! Why, I've just begun! I'll find *more* Jefferson Smiths! I'll clean out of our glorious state every *vestige* of James Taylor--I'll--
Now we are in a STREET, in daylight, with the BOY RANGER BAND marching--playing a martial air--confetti falling on them. JEFFERSON AND SAUNDERS are in the back of an open car--band--cheers--confetti! They are both rather dazed. A huge placard, carried by a Boy Ranger, reads: "JEFFERSON TO THE SENATE FOR LIFE!" There is a BAND, and there is much cheering. Then the GOVERNOR AND MRS. HOPPER are seen in the back of an open car. (Band and cheers and confetti.) Happy is bowing to left and right-- all smiles. He pauses to say:
HUBERT: Emma--it's the White House--no less!
JEFFERSON AND SAUNDERS are in the open car; Jeff looks off, and is suddenly at attention. In a GROUP ON THE SIDEWALK, Joseph Paine is watching the parade. Suddenly Jeff leaps out of the car and heads for the curb. Saunders tries to stop him. JEFF is pushing through the crowd--and grabbing for PAINE, who has fearfully started to move off.
JEFFERSON: Please, sir!--come with me!
PAINE: No, Jeff--please--!
JEFFERSON: I say it's *your* parade, sir! You've *got* to come!
He pulls Paine with him--back toward the automobile. The people mill around them. The scene dissolves to the SMITH LIVING ROOM, as Jeff and Saunders and Paine enter to Ma, who is waiting. (Outside we still hear the band and cheers.)
MA (kissing Jeff's cheek): Hello, Jefferson.
JEFFERSON: Hello, Ma. (Indicating Saunders) Clarissa, Ma. She'll be stayin' a while--
MA (takes Saunders' hands): Fine--
JEFFERSON: And Senator Paine too, Ma--we'd like to have him--
MA (warmly): Certainly would, Joseph.
JEFFERSON: How's Amos, Ma?
MA: Just fine.
JEFFERSON (taking Saunders' hand): We'd better see.
SAUNDERS: Jeff--wait--they want you to speak!
JEFFERSON: Not *me*! Joseph Paine is the man they ought to be listening to! Come on!
He drags her off toward pet shop--Paine calling after him, protesting. And in the PET SHOP: Saunders and Jeff are seen entering. On seeing Jeff, the animals go berserk. And in a comparative lull Jeff says to them:
JEFFERSON: Meet Clarissa, fellas.
And the scene fades out.